1. Field of the Invention
The present invention relates to an improved articulator of the type designed to grind in the masticatory surfaces of an upper and lower jaw portion of a dental prosthesis model. More specifically, in an articulator of the type having two reproduction bodies, each three-dimensionally movable in relation to the other to copy a patient's articulative movements, the improvement includes compensation means connected to one of the reproduction bodies to provide three-dimensional adjustment of a jaw model in relation to the reproduction body.
2. Description of the Prior Art
The movements of a set of teeth, whether a natural set, one provided with bridges and inserted teeth, or one consisting of dental prostheses, are composed of the articulation movements of the lower jaw and, in the case of an artificial denture, of the individual movements of the prostheses support structures elastically fitted on the mucuous membrane. An exact three-dimensional measurement and recording of these composite movements and the most complete possible simulation of these movements on an articulator are absolutely necessary in order to render possible grinding in of the masticatory surface relief in such a way that incorrect settings and temporary or permanent over-stressing of the temporo-mandibular joints (jaw joints) and especially of the condyles (jaw joint heads) can be excluded. This is particularly important because according to the latest knowledge, the lasting over-stressing of the jaw joints, due to an incorrect position of the lower jaw by reason of a defective occlusion of the jaws, can have far-reaching consequences in the well-being of the person, and can inter alia be the cause of migraine.
Measuring instruments are known wherein the movements of the lower jaw and the exact positions of the parts of the set of teeth of the patient may be recorded. Further, articulators have been provided that cooperate with such measuring instruments to grind in the mastication surface profiles of a set of artificial teeth, wherein the upper and lower jaw models may be articulated with respect to each other to copy the patient's articulative motions. U.S. Pat. No. 3,552,020, of common inventorship herewith, describes such an articulator wherein the movements of the lower jaw in relation to the upper jaw can be copied practically perfectly.
This known articulator, which is acknowledged by science and is already used by dentists, despite all the advantages which it offers in relation to the reproducibility of the masticatory movements, still possesses a disadvantage which should not be underestimated. This consists in that as a result of uncontrollable plaster expansion, the jaw model is moved out of its correct position during the setting of the plaster that connects its base with the associated part of the articulator. Accordingly, the occlusion on the articulator is no longer in conformity with the effective occlusion measured on the patient, or the condyle positions on the articulator differ from the actual positions of the jaw joints in the patient. Thus, certain masticatory surface profile errors, even though slight, are unavoidable.
Therefore, it is an object of the present invention to provide an improved articulator wherein inaccuracies due to the setting of the jaw plaster models can be compensated and corrected, in order to precisely reproduce the jaw movements of the patient to guarantee a perfect reproduction of the occlusion conditions on the articulator.